Hey Csaba,
I will use the same order for the answers as before:
1). Please excuse me, yet I’m still not sure I understood what exactly you are trying to achieve. Do you want the thumbnails (i.e. featured images to display below the titles for single portfolio projects?
2). The template function you need is “get_the_terms”; you can read more about it on the official WordPress website here.
Sincerely,
Andrii / Satori Studio